Besides a while loop, you can work on each of a list of files
with recursion. A recursive version of lengths-list-many-files
is short and simple.
The recursive function has the usual parts: the `do-again-test', the
`next-step-expression', and the recursive call. The `do-again-test'
determines whether the function should call itself again, which it
will do if the list-of-files contains any remaining elements;
the `next-step-expression' resets the list-of-files to the
CDR of itself, so eventually the list will be empty; and the
recursive call calls itself on the shorter list. The complete
function is shorter than this description!
(defun recursive-lengths-list-many-files (list-of-files)
"Return list of lengths of each defun in LIST-OF-FILES."
(if list-of-files ; do-again-test
(append
(lengths-list-file
(expand-file-name (car list-of-files)))
(recursive-lengths-list-many-files
(cdr list-of-files)))))
In a sentence, the function returns the lengths' list for the first of
the list-of-files appended to the result of calling itself on
the rest of the list-of-files.
Here is a test of recursive-lengths-list-many-files, along with
the results of running lengths-list-file on each of the files
individually.
Install recursive-lengths-list-many-files and
lengths-list-file, if necessary, and then evaluate the
following expressions. You may need to change the files' pathnames;
those here work when this Info file and the Emacs sources are located
in their customary places. To change the expressions, copy them to
the `*scratch*' buffer, edit them, and then evaluate them.
The results are shown after the `=>'. (These results are for files from Emacs Version 18.57; files from other versions of Emacs may produce different results.)
(lengths-list-file
"../lisp/macros.el")
=> (176 154 86)
(lengths-list-file
"../lisp/mailalias.el")
=> (116 122 265)
(lengths-list-file
"../lisp/makesum.el")
=> (85 179)
(recursive-lengths-list-many-files
'("../lisp/macros.el"
"../lisp/mailalias.el"
"../lisp/makesum.el"))
=> (176 154 86 116 122 265 85 179)
The recursive-lengths-list-many-files function produces the
output we want.
The next step is to prepare the data in the list for display in a graph.
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